Abstract from the original paper :
Background
Glioblastoma (GBM) is the most devastating brain tumor. Despite the use of multimodal treatments, most patients relapse, often due to the highly invasive nature of gliomas. However, the detection of glioma infiltration remains challenging. The aim of this study was to assess advanced PET and MRI techniques for visualizing biological activity and infiltration of the tumor.
Methods
Using multimodality imaging, we investigated [18F]DPA-714, a radiotracer targeting the 18 kDa translocator protein (TSPO), [18F]FET PET, non-Gaussian diffusion MRI (apparent diffusion coefficient, kurtosis), and the S-index, a composite diffusion metric, to detect tumor infiltration in a human invasive glioma model. In vivo imaging findings were confirmed by autoradiography and immunofluorescence.
Results
Increased tumor-to-contralateral [18F]DPA-714 uptake ratios (1.49 ± 0.11) were found starting 7 weeks after glioma cell implantation. TSPO-PET allowed visualization of glioma infiltration into the contralateral hemisphere 2 weeks earlier compared with the clinically relevant biomarker for biological glioma activity [18F]FET. Diffusion-weighted imaging (DWI), in particular kurtosis, was more sensitive than standard T2-weighted MRI to detect differences between the glioma-bearing and the contralateral hemisphere at 5 weeks. Immunofluorescence data reflect in vivo findings. Interestingly, labeling for tumoral and stromal TSPO indicates a predominant expression of TSPO by tumor cells.
Conclusion
These results suggest that advanced PET and MRI methods, such as [18F]DPA-714 and DWI, may be superior to standard imaging methods to visualize glioma growth and infiltration at an early stage.
![Images TEP réalisées après injection du radiotraceur [18F]DPA-714, une, trois, cinq, sept et neuf semaines après l'implantation de cellules de glioblastomes dans le striatum d'un rongeur. Les traits blancs délimitent la boîte cranienne. Trois zones sont délimitées par des cercles blancs : une zone autour du point d'injection des cellules tumorales (droite), la zone équivalente dans l'autre hémisphère (milieu), et le corps calleux (gauche). Ces images indiquent que la tumeur croit au cours du temps et inflitre l'autre hémisphère cérébral. © Pigeon et al. Oxford University Press](/drf/joliot/PublishingImages/Actualites/Actualites/Actualites_scientifiques/2019/PigeonEtAl-NeuroOncology.png)